The VGT Level-2 data exhibit an ortho-geolocation grid defining longitude, latitude and altitude for each pixel. For resampling onto the VGT P grid, the direct and inverse geo-location approximations in the VGT Level-2 grid are needed.

VGT 1 km Plate-Carrée grid cell (green square)

The SPOT VGT Plate-Carrée grid has 112 pixels per degree, which corresponds to an equatorial resolution of approximately 1 km. The projection of the VGT Level-2 product results in the VGT-P product.

The latitude and longitude coordinates of each pixel are taken into account to fill the Plate-Carrée boxes.

The projection algorithm is then straightforward. For each target pixel the corresponding source pixel is filled by means of parameters associated with all SYN reference pixels included in this target pixel.